POWERFUL FORCE: We often take the sun for granted because it is a constant to be expected.
THE morning sky streaked red, yellow and orange across the horizon reflecting onto the still blue water until the sky and the water appeared as one. The old wives saying, ‘red sky in morning, sailors take warning’, was out of place on the peaceful beach. The calmness of the morning would surely continue for the day.
The sun is the centre of our lives. We can forget this, because as the Earth rotates from day to night and back, it is a constant to be expected. It is a mysterious constant even in today’s age of technology. Ancient peoples explained and worshipped it according to their experiences. To explain day and night, for example, ancient people believed that the sun rode on a barge or a chariot. Nowadays, we know that this occurs because the Earth rotates on its axis around the sun, our closest star.
The sun was also worshipped as a god or goddess in the ancient world including by the Egyptians, Inca, Aztecs, Romans and Greeks. According to a Chinese myth, there once were 10 suns, all young men who enjoyed playing. They decided to go up into the sky at the same time and it was so hot that nothing would grow. The hero, Hou Yi, saved the day by shooting down nine. Another myth originating in China is that a solar eclipse is caused by a magical dog taking a bite out to the sun. So to scare off the dog and save the sun, you must make a lot of noise. Ancient structures were built and some, for example, the famous Stonehenge in Southern England, mark the summer solstice, the longest day of the year, and the winter solstice, the shortest day of the year.
A quick search reveals that much has been learned about the sun (which has led to more questions) over the ages from when Galileo was the first to observe it through a telescope. Now it is being seen up close via unmanned spacecraft.
The sun is a ball of liquid plasma interwoven with a magnetic field. It is composed of 75 per cent hydrogen, 24 per cent helium and about 1 per cent heavy metals. Our dynamic changeable star has several layers (refer to the diagram). Let’s start with the core and work our way outwards.
The core is where energy originates through nuclear fusion and its temperature of 27 million degrees Fahrenheit. The next zone is the radiative zone. Here heat and energy travel outwards towards the convection zone. Convection is what brings bubbles of air to the surface of a pot of boiling water, and on the sun the temperature is a cool two million degrees Fahrenheit. The heat is moved along thermal columns to the next zone, the photosphere, which is what we see. The thermal columns, of the convection zone, make this zone appear pitted when we look up into the sky and look at the sun.
Sunspots and solar storms occur in the photosphere which is 10,000 degrees Fahrenheit. The chromosphere occurs just above. This zone contains huge solar flares and hot gas shoots up for thousands of miles. The temperature here has risen and it is estimated to be 50,000 degrees Fahrenheit. The final layer is the corona, which is only visible during a total solar eclipse. This layer is estimated to be four million degrees Fahrenheit, and this heat is one of the mysteries of the sun.
Whenever the sun is in the news, terms such as solar wind, solar storms, and sunspots are batted about. What do these terms mean? For example on Aug 7, I read an online news report that warned a solar storm could disrupt satellite communication. A solar storm refers to activity on the sun and this could include solar winds, which refer to hot gases streaming from the sun. It could also include sunspots where there is high magnetic action. Solar storms can and do affect the weather and climate on Earth.
As mentioned, we are completely dependent on the sun. Photosynthesis – the process by which plants transform carbon dioxide and water into carbohydrates – requires sunlight as the primary source of energy. However, the sun, or the rather the climate, can be just too hot. In July, Canada and the US baked under the sun and even here we were commenting on the unusually hot weather.
Living organisms have adapted to the mind-boggling number of habitats and ecosystems that are present on Earth, including the intensity of ultraviolet light, which is blamed for skin cancer.
The sun is a powerful force, one which we take for granted, and one which we may not even realise is affecting us daily.